Electronic sequence-timing switch



Jan. 12, 1960 H. u. NE IDHART 2,921,195

ELECTRONIC SEQUENCE-TIMING SWITCH Filed Nov. 12, 1957 I verrtorz' United States Patent '0 ELECTRONIC SEQUENCE-TIMING SWITCH Hans Ulrich Neidhartlt, Zurich, Switzerland, assignor to H. A. Schlatter Aktiengesellschaft, Zollikon, Zurich, Switzerland Application November 12, 1957, Serial No. 695,970

Claims priority, application Switzerland November 15, 1956 7 Claims. (Cl. 250-47,)

The present invention concerns electronic sequencetiming switches and more particularly a type thereof which is especially designed and useful for'controlling program-controlled electric welding apparatus. In switches of this type a special time control unit is provided for each section or stage of the program to be carried out, and each of these time control units mainly consists of two grid controlled gas discharge tubes having cathodes, respectively, which are connected to line voltage via a resistance and are capacitance coupled with each other. The first of said two tubes is blocked ,by a negative bias potential of its grid circuit while the unit is in non-operative condition, but this first tube is ignited by an impulse transmitted to its igniting grid; thesecond one of said tubes is in ignited condition and operating while the unit itself is in non-operative condition, but said second tube is extinguished by an impulse that ignites the first tube, after which the second tube is ignited again by means of a gradually increasing potential applied thereto. Their performance is illustrated by a timecurrent diagram of almost rectangular shape.

If it is desired to unite or combine a plurality .of such time control units to form a sequence-timing switch for carrying out a certainscheduled program, thenit is necessary that by the re-ignition of the second tube of each time control unit the first tube of the next following time control unit is ignited so that the control impulse impressed upon the first time controlunit of the whole :chain passes step by step and in a predetermined sequence the various time control units in predetermined intervals. It has been found however that such a step by step trans mission of the initial impulse in defined intervals has not been possible so far with the required precision and reliability because the performance was frequently disturbed and affected by misfirings. This'is due to the fact that at the time when the first time control unit is actuated or energized a certain impulse is :already transmitted to the first tube of the next following unit'or-stage.

It is therefore a main object of the present invention to eliminate these disturbing factors and to assure an entirely precise and reliable performance of a combination or chain of individual time control units intended to act as an electronic sequence-timing switch.

With above object in view a switch arrangement according to the invention comprises a plurality of time control units coupled with each other in a predetermined sequence by means of a line Which connects a grid of the second tube of the first stage or unit with the. igniting grid of the first tube of the next following stage or unit. Preferably a rectifier is connected in said line in such a manner that this rectifier allows only positive impulses to pass. It is further advisable to use in each time control unit a two-grid tube as the second tube, one of these grids being used for synchronizing purposes while the other grid serves for transmitting the igniting impulse.

The novel features which are considered as characteristic for the invention are .set forth in particular in the appended claims. The invention itself, however, .both as age peaks. A resistor 31 .(31) serves in this connection to its construction and its method of operation, together With additional objectsand advantages thereof, w1ll be best understood from the followingdescription of specific embodiment when read in connection with the accompanying drawing, which illustrates the arrangement and circuit diagram of two time control units I and II as a preferred embodiment of the present invention.

The embodiment illustrated and described below is an arrangement which is particularly suitable for being used as an electronic time-sequence switch for controlling a program-schedule electric welding apparatus.

The two time control units '1 and II as shown by way of example, control two consecutive program stages and are essentially identical with each other. Therefore like elements of the two stages or units are marked with the same reference numerals except that the numerals of the second unit II are primed;

Each one of the time control units comprises two gas discharge tubes '1, 2 (1, 2 thecathodes of which are coupled with each other via a condenser 3 '(3), While each cathode is connected via a cathode resistor .4, 5, respectively, (4, 5, respectively) with the minus pole of the source of anode potential. The anodes of the various tubes are all connected with the positive vpole .of this source of potential. Each of the four tubes has .two grids. The grid 28 (28) of the 'first tube 1 (1') serves.

for stabilizing the igniting voltage and is connected via a resistor 26 (26') with the cathode while the other grid 27 (27') serves as igniting grid and is supplied with a 13 (13) of similar magnitude is connected between one of the A.C. terminals of-the rectifier 6 (6') and the negative end of the cathode resistor 4 (4). The voltage drop along the cathode resistor '5 (5) of thesecond tube 2 (2') is applied through-a valve 14 (14) to the terminals of a parallel combination-of a condenser 15 (15') and a resistor .16 :(16'.) which serves to produce a gradually increasing potential which is impressed upon the grid '29 (29') of the second tube'Z (2) via a resistor 33 (33').

The A.C. voltage which serves for synchronization pur poses is transmitted to the first grid 30 (30) which is closest to the cathode of.the tube 2 (2') by mean of a transformer 17 (17') which'is preferably operated with an oversaturated core inorder to furnish pronounced voltfor limiting the grid circuit while a battery 34 (34') producesa negative grid bias potential so that it is possible, to arrange 1for:the ignition to occur atan exactlypredetermined phase of the synchronizing A.C. voltage. v

The output control voltage is transmitted to the an paratus or machine controlled thereby, from the movable tap of the cathode'resistor 4 (4) ofeach of the respective time control units. The just-mentioned tap is connected, for this purpose, with 'an-output or control terminal 18 (18'). The igniting impulse for the subsequent time control unit II is furnished by the grid 29 of the second tube 2 of the first unit and is transmitted through a line connection 35 via a valve 24 and the condenser 12 to the grid 27' of thezfirst tube 1' of'the second'time control unit II. Inorder to make sure that the layers of the condenser 12 have a definite and predetermined potential while not operative, the rectifier valve 24 is shunted by a high ohmic resistor 23.

In a similar manner 'the I grid 29' of the .tube .2 may be connected by a similar connecting line to the terminal 20 and from there to the first tube of a third unit and so on. For the purpose of stabilization the condensers 21, 22, 25, 32 (21', 22, 25', 32) are provided and arranged in a generally well known manner.

The operation of the whole arrangement is as follows: The anode potential of the tubes 1 and 2 (1 and 2') is chosen to be lower than the potential at which the tubes would ignite and higher than the potential at which the tubes would extinguish. The grid bias potentials are chosen so that when the arrangement is non-operative the tubes 2 and 2 are ignited and working while the tubes 1 and 1' are blocked. The bias potential at the grids 30 and 30 is chosen so high that the tubes 2 and 2, when extinguished, are only ready to be ignited again when a positive voltage peak of the synchronizing A.C. voltage is applied thereto. Now, if the whole arrangement is connected to the line voltage, first the tubes 2 and 2 will be ignited because an A.C. voltage is applied to the transformers 17 and 17 and since there is no voltage drop yet that would appear at the resistor and 5, respectively. The appearance of such a voltage drop is delayed by the condenser 15 (15'). After the tubes 2 and 2' have been ignited, they cannot, being gas discharge tubes, be extinguished as long as their anode potential is higher than the potential at which they would extinguish. Consequently, these tubes can only be extinguished by a temporary lowering of their anode potential.

The conditions in the components of the arrangement which serve to gradually change the voltage, are stationary ones. The cathode current of the tube 2 (2') is split and distributed among the two resistors 5 and 16 (5' and 16"); a voltage drop caused hereby in the latter is applied to the grid 29 (29). The condenser 3 (3') is so charged by the voltage drop across the resistor 5 (5') that the layer thereof appearing in the drawing at the right hand is positive, while the layer appearing at the left is negative.

As soon as now a first starting impulse is introduced through the input terminal 19 and transmitted to the grid 27, the tube 1 is ignited. Hereby a voltage drop appears at the cathode resistor 4 which causes the condenser 3 to discharge because now the cathodes of the tubes 1 and 2 have practically the same potential. The corresponding discharge current increases temporarily the voltage drop at the resistors 5 and 16 so that the cathode potential of the tube 2 becomes temporarily more positive and therefore extinguishes this tube. Thereupon the condenser 3 is now charged in opposite direction that is charged positive at the left hand side while the voltage drop at the resistor 5 is reduced to zero. Consequently, the condenser 15 of the gradual voltage change means 15, 16 starts to discharge through the resistor 16. The speed of this discharging action is solely determined by the components 15, 16 because the valve 14 is a block in the direction of this discharging current. When the negative bias potential transmitted from the combination 15, 16 to the grid 29 has sufiiciently changed in negative direction the tube 2 is ignited as soon as thereafter a voltage peak of the synchronizing A.C. voltage is transmitted from the trans former 17 to the grid 30. Hereby the tube 1 is extinguished due to the discharge of the condenser 3 in the same manner in which previously the tube 2 has been extinguished by the tube 1. At the same time the voltage drop caused by the discharging current of the condenser 3 in the resistor 4 creates a high negative potential at the grid 27 of the tube 1 so that this tube does not ignite again until the next starting impulse reaches the condenser 12.

When the tube 2 re-ignites in the above-described manner a certain rise of potential appears at the grid 29. This positive voltage impulse is transmitted via the valve 24 and the condenser 12 to the grid 27' of the first tube 1' of the second time control unit 11 and serves as the igniting impulse for the next stage of the program or schedule.-

Consequently, now the tube 1' is ignited and furnishes at the terminal 18' the control voltage for the machine apparatus to be controlled, for the second stage of the program. The tubes 1' and 2 cooperate further in the same manner as it has been described above in reference to the tubes 1 and 2. Evidently, an igniting impulse for another stage can be obtained from the grid 29' via the connecting line and terminal 20 so that hereby a third stage of the program can be controlled. In the same manner the whole performance can be continued through an infinite chain of time control units for a corresponding number of stages or steps of the program. It should be noted that in this manner for the individual stages and in the individual control circuits voltage changes are obtained which would appear in a diagram as approximately rectangular forms closely following each other.

The negative bias potential of the grid 30 (30') can be furnished, instead of from the grid battery 34 (34'), by a unidirectional valve connected to the transformer 17 so as to be supplied with A.C. voltage thereby. The justmentioned valve is preferably combined with a condenser and with a leakage resistor to constitute a small rectifier unit in itself.

The fact that one grid of the second tube of a particular time control unit is being used for transmitting an impulse to the first tube of the subsequent time control unit safely prevents this subsequent unit to be actuated prematurely, i.e. particularly already by the extinguishing impulse which is transmitted to the cathode of the tube 2. This is due to the fact that this extinguishing impulse temporarily raises the potential of the cathode of the tube 2 above the potential of its own anode whereby also the connected potential of the combination 15, 16 is raised so that in fact only the grid 29 takes care of an undisturbed coupling for the tube 1'. During the time interval during which the first time control unit I completes its cycle of operation, the second tube of this first time control unit is without current or does not pass any current so that none of the various changes of voltage which occur in the various circuits of the first time control unit I can reach the grid 29 (29) of the second tube. However, at the moment when the second tube of said first time control unit is re-ignited the cycle of this first time control unit is completed. At this moment the grids of there-ignited tube becomes due to accumulation of ions suddenly very strongly positive so that the grid 29 transmits to the grid 28' of the next following tube 1' a strong igniting impulse via the condenser 12'.

Very essential for the reliable operation and performance of the arrangement shown in the drawing is the resistor 13 in which an increased voltage drop is created at the moment of the re-ignition of the tube 2, said voltage 3 drop imparting to the grid 27 a higher negative bias potential. Even if the grid resistor 11 (11) is chosen to be very high in order not to weaken the igniting impulse for the tube 1 (1), at the moment of the abovementioned extinguishing impulse a negative charging current of so great strength is applied to the grid 27 that the inner grid circuit of the tube 1 (1) is overcome and it is sure that during the breakdown of the anode potential the required blocking voltage is developed at this grid before the tube is ready to be reignited.

ll: will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of sequence-timing switches differing from the types described above.

While the invention has been illustrated and described as embodied in electronic sequence-timing switches, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Electronic sequence-timing switch, particularly for controlling program-controlled electrical Welding apparatus, comprising, in combination, line voltage means; a series of time control units, each of said units including a first and a second grid-controlled gas-discharge tube having cathodes capacitance-coupled with each other, cathode resistors respectively connected between said cathodes and said line voltage means, means for blocking said first tube by applying a negative bias potential to its grid circuit while the particular unit is non-operative, means for igniting said first tube by transmitting a voltage impulse to its grid, means for keeping said second tube ignited while the particular unit is non-operative, interconnecting means between said first and second tubes for causing said second tube to be extinguished by an igniting impulse imparted to said first tube, and for caus-,

ing said first tube to be extinguished by an igniting impulse imparted to said second tube, means for creating a gradually increasing potential and for applying it to the grid circuit of said second tube for re-igniting the latter after it has been extinguished by said igniting impulse of said first tube, and an impulse input terminal connected to the igniting grid of said first tube; a line connection between a grid of the second tube of every one of said time control units and said impulse input terminal of the first tube of the next following one of said series of time control units; and in each of said time control units an output terminal connected to the cathode resistor of the firsttube of the particular time control unit for delivering the desired control impulse at the time when the first tube of the particular time control unit is operated.

2. An electronic sequence-timing switch as set forth in claim 1, said second tube of each time control unit being equipped with two grids of which one serves for igniting said tube and is connected to said means for creating a gradually increasing potential so as to obtain the required igniting voltage therefrom, while the other one of said grids serves to accumulate ions and is connected to said line connection for transmitting in igniting impulse to the next following time control unit.

3. LAD electronic sequence-timing switch as set forth in claim 2, including a synchronizing transformer and means for furnishing a negative bias potential connected in series between said igniting grid of said second tube and said means for creating a gradually increasing potential.

4. An electronic sequence-timing switch as set forth in claim 1, including valve means inserted in said line connection between consecutive time control units, said valve means being so connected that only positive impulses are allowed to pass from said other grid of said second tube of one time control unit to the igniting grid of said first tube of the next following time control unit.

5. An electronic sequence-timing switch as set forth in claim 1, including a connecting resistor connected between the positive pole of said means for applying a negative bias potential to the grid circuit of said first tube, and the negative pole of said cathode resistor of said second tube so that at the moment of ignition of said second tube the negative grid bias of said first tube is abruptly increased.

6. An electronic sequence-timing switch as set forth in claim 5, including a grid resistor inserted in the grid circuit of said first tube, the resistance of said connecting resistor being smaller than that of said grid resistor.

7. Electronic sequence-timing switch, particularly for controlling program-controlled electrical welding apparatus, comprising, in combination, line voltage means; a series of time control units, each of said units including a first and a second grid-controlled gas-discharge tube having cathodes capacitance-coupled with each other, cathode resistors respectively connected between said cathodes and said line voltage means, means for blocking said first tube by applying a negative bias potential to its grid circuit While the particular unit is non-operative, means for igim'ting said first tube by transmitting a voltage impulse to its grid, means for keeping said second tube ignited while the particular unit is nonoperative, interconnecting means between said first and second tubes for causing said second tube to be extinguished by an igniting impulse impanted to said first tube, and for causing said first tube to be extinguished by an igniting impulse imparted to said second tube, means for creating a gradually increasing potential and for applying it to the grid circuit of said second tube for re-igniting the latter after it has been extinguished by said igniting impulse of said first tube, and an impulse input terminal connected to the igniting grid of said first tube; a line connection between a grid of the second tube of every one of said time control units and said impulse input terminal of the first tube of the next following one of said series of time control units;

and in each of said time control units an output terminal connected to the cathode resistor of the first tube of the particular time control unit for delivering the desired control impulse at the time when the first tube of the particular time control unit is operated; said second tube of each time control unit being equipped with two grids of which one serves for igniting said tube and is connected to said means for creating a gradually increasing potential so as to obtain the required igniting voltage therefrom, while the other one of said grids serves to accumulate ions and is connected to said line connection for transmitting 'an igniting impulse to the next following time control unit; a synchronizing transformer and means for furnishing a negative bias potential connected in series between said igniting grid of said second tube and said means for creating a gradually increasing potential; valve means inserted in said line connection between consecutive time control units, said valve means being so connected that only positive impulses are allowed to pass from said other grid of said second tube of one time control unit to the igniting grid of said first tube of the next follo wing time control unit; a connecting resistor connected between the positive pole of said means for applying a negative bias potential to the grid circuit of said first tube, and the negative pole of said cathode resistor of said second tube so that at the moment of ignition of said second tube the negative grid bias of said first tube is abruptly increased; a grid resistor inserted in the grid circuit of said first tube, the resistance of said connecting resistor being smaller than that of said grid resistor.

References Cited in the file of this patent UNITED STATES PATENTS Levoy Oct. 19, 1943 

